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Register a new userHigh Strength Concrete in Local Materials Preparing &Studying its Qualities and Behaviour
البيتون عالي المقاومة بالمواد المحلية, تحضيره, و دراسة خواصه و سلوكه.
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Added by
Tishreen University ورقة بحثية
Publication date
2015
fields
Structural Engineering
and research's language is
العربية
Created by
Shamra Editor
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برزت أهمية البيتون عالي المقاومة في الآونة الأخيرة لدخوله في تصنيع أغلب عناصر و أجزاء المنشآت البيتونية, و كذلك في تنفيذ المنشآت المدنية الخاصة, كقواعد الجسور و الأبراج العالية و الأعمدة و المنصات التي تحمل المنشآت النفطية, في البحار و المحيطات. يهدف البحث إلى تصيمم خلطات بيتونية ذات مقاومات أسطوانية (55-65-75) MPa وفق الكود الأمريكي ACI-211-4R-93 ,و ذلك باستخدام إحضارات محلية و إضافات مناسبة, مع شرح لطريقة التصميم المستخدمة. و من ثم دراسة تغيير مخطط ) الإجهاد – التشوه ) تجريباً على الضغط البسيط للعينات السابقة, و ذلك من خلال الأجهزة المتوفرة , و تمت مقارنتها مع المخططات التي تم الحصول عليها حسابياً. تم تقييم قانون السلوك لمخطط (الإجهاد – التشوه) و معامل المرونة المأخوذ من المخطط . استنتجت مجموعة من النتائج و التوصيات الخاصة بالموضوع و التي تمكن من تطبيق نتائج البحث على أرض الواقع.
Recently, the importance of high Strength concrete has appeared due to its application in manufacturing most of the concrete structures and members, as well as to its importance in the implementation of civilian facilities like bridge bases, skyscrapers and in implementing the columns and platforms which carry oil installations carried out in the oceans and seas. The research aims to design concrete mixtures with cylindrical resistors ( 55- 65- 75 Mpa) according to the American code AcI-211-4R-93 by using local and appropriate additions as well as explaining the method used in designing. Then, studying the transformation in stress strain curve – deformation (σ- ζ ) undergoing a simple pressure on the previous samples throughout the available devices. Then, it was compared to the charts obtained mathematically .Law behaviour of stress strain and deformation curve was rated, in addition to modulus of elasticity taken from the chart. Couple of results and recommendations related to the issue were concluded, those which were applied in praxis.
Artificial intelligence review:
Research summary
تتناول هذه الدراسة إعداد البيتون عالي المقاومة باستخدام مواد محلية ودراسة خواصه وسلوكه. يهدف البحث إلى تصميم خلطات بيتونية ذات مقاومة اسطوانية تتراوح بين 55-65 ميغاباسكال وفقًا للكود الأمريكي ACI-211-4R-93 باستخدام مواد محلية وإضافات مناسبة. تم اختبار العينات تجريبياً لدراسة مخطط الإجهاد-التشوه تحت الضغط البسيط ومقارنتها مع المخططات الحسابية. تم تقييم قانون السلوك ومعامل المرونة المستخلص من المخطط. توصلت الدراسة إلى مجموعة من النتائج والتوصيات التي يمكن تطبيقها عملياً، مثل زيادة مقاومة البيتون باستخدام كميات أكبر من الإسمنت ورماد السيلكا، وتزايد معامل المرونة بزيادة المقاومة. كما أظهرت النتائج تطابقاً بين النتائج التجريبية والحسابية مما يدل على صلاحية العلاقة المستخدمة من هيئة الاتحاد الأوروبي للبيتون المسلح عالي المقاومة.
Critical review
تعتبر هذه الدراسة مهمة للغاية في مجال الهندسة المدنية، حيث تقدم حلولاً عملية لاستخدام البيتون عالي المقاومة في المنشآت المختلفة. ومع ذلك، يمكن أن تكون الدراسة أكثر شمولية إذا تم تضمين تحليل اقتصادي لتكلفة المواد المحلية مقارنة بالمواد المستوردة. كما أن الدراسة قد استفادت من استخدام تقنيات تحليل متقدمة لتقييم سلوك البيتون تحت ظروف مختلفة من الأحمال والبيئات. بالإضافة إلى ذلك، يمكن تحسين الدراسة من خلال تقديم تفاصيل أكثر عن كيفية تطبيق النتائج في مشاريع حقيقية وتقديم دراسات حالة لتوضيح الفوائد العملية.
Questions related to the research
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ما هو الهدف الرئيسي من هذه الدراسة؟
الهدف الرئيسي هو تصميم خلطات بيتونية ذات مقاومة اسطوانية تتراوح بين 55-65 ميغاباسكال باستخدام مواد محلية وإضافات مناسبة، ودراسة خواص وسلوك هذه الخلطات تحت الضغط البسيط.
-
ما هي المواد المضافة التي تم استخدامها في الخلطات البيتونية؟
تم استخدام مواد مضافة مثل الرماد المتطاير (Fly Ash)، خبث الأفران الحبيبي، ورماد السيلكا لزيادة مقاومة البيتون وتقليل نسبة الماء المطلوبة.
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ما هي النتائج الرئيسية التي توصلت إليها الدراسة؟
توصلت الدراسة إلى أن زيادة كمية الإسمنت ورماد السيلكا تزيد من مقاومة البيتون، وأن هناك تطابق بين النتائج التجريبية والحسابية مما يدل على صلاحية العلاقة المستخدمة من هيئة الاتحاد الأوروبي للبيتون المسلح عالي المقاومة.
-
كيف تم تقييم قانون السلوك ومعامل المرونة للبيتون عالي المقاومة؟
تم تقييم قانون السلوك ومعامل المرونة من خلال دراسة مخطط الإجهاد-التشوه تحت الضغط البسيط للعينات التجريبية ومقارنتها مع المخططات الحسابية.
References used
ACI 211-4R-93 :Guide for selecting proportions for high –strength the concrete with Portland cement and fly ash
Astm c 150- Standard Specification for Portland Cement
Canadian Standards for design of concrete structures ,CSAA-233-94 ,Rexdale Ontario Canada Dec 1994 ,pp199
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This research presents an experimental study behaviour of high strength concrete, for
evaluation of stress - strain curve and derivation of factors of equivalent compressive
stress block, we depend it in design of high strength concrete elements.
For this purpose, number of cylinders specimens with strength 60 MPa were prepared
and tested in compression, then curve was obtained.
The results showed the possibility of producing high strength concrete from local
materials and with strengths are highest than those were obtained, the resulting diagrams of
curve are shown to be essentially linearly elastic up to failure with a steeper declining
portion of the stress - strain diagram, which agree with the results of global researches, the
failure was almost sudden and rapid with increasing strength which shows that the highstrength
concrete less ductile than normal concrete at the failure. Curve of high strength
concrete differs from that normal concrete, this affects on the properties of rectangular
equivalent stress block which requires modifications on the factors led to optimum represent
for it and with evaluation of curve of the tested specimens, the diagram takes a
trapezoidal shape ( ), its value at the top is and the depth of the compressive
block is and we found and ( is average compression/cylinder
compressive strength of concrete, is ratio of the active depth that defined location of
compression force center), when concrete strength increases up , the diagram
shape will be closer to triangular than trapezoidal and then curve takes the shape of triangle its
value at the top is and the depth is and with replacing triangular diagram to rectangle.
This research presents an experimental study about the effect of steel fibers on the
main variables of stress- strain curve for high strength concrete on simple compression,
which are: shape of stress- strain curve, ductility factor, energy absorpt
ion capacity. For
this purpose, series of cylinders concrete specimens were prepared in compressive strength
(70 MPa). the steel fiber with aspect ratio of L/D =70 were added at the volume fractions
of (0-1-1.5-2)%. The cylinders were tested under a monotonic loading at compression, and
as a result of the tests, the total curve of stress- strain was obtained. The experimental
results of research showed a positive effect of steel fibers on the behavior of high strength
concrete, this effect increased with increasing volume fraction of steel fibers. It can be seen
from stress-strain curve, whereas the slope of the ascending branch is not much affected.
The descending branch of the stress- strain curve decreases by the increase in the fiber
volume fraction. This means the ductility and toughness improve with the addition of steel
fibers and as a result the behavior of high strength concrete has gone far away from being
brittle as it is used to be.
This paper is devoted to investigate the effect of high temperatures on the behavior
and compression resistance of rectangular high-resistance concrete samples.
In this study, rectangular samples with dimensions of (15X15X15 cm) have been
made and
after 28 days they have been burned in a special oven, then cooled down in the
air.
The exposition of high-resistance concrete samples which made of local sand and
aggregate and use silica fumeoiiuk to high temperatures has led to a reduction and lose in
the compressive resistance of this samples.
When the temperature was 350 c, the reduction in the compressive resistance was
about 13%, and at the temperature of 450c, the reduction was about 36%, and at the
temperature of 850c, the reduction was about 72%.
Therefore, we have to take this reduction of compressive resistance in the concrete
elements seriously when they exposed to fire, so we can take the right decisions about
rehabilitation or conservation or replacement of this elements.
Featuring a self-compacting concrete (SCC) high capacity to fill the mold and
passing ability through barriers under the influence of self-weight without vibration,
thereby reducing the required labour and reduces the noise associated with vibratio
n.
Modern applications focused on improving the specifications of high performance,
resistance and speed of construction. The research presents an experimental study for an
(SCC) mix produced from local materials, including the necessary tests on the proposed
concrete mix, which approved in the global codes. These experiments determine the basic
characteristics of (SCC) in fresh case were also identified pressure resistance of (SCC) and
determine the value of the modulus of elasticity (E) and the behavior curvatures. All mixes
have been achieved global standards and conditions, and the required experiments were
done in the laboratory of civil engineering faculty at Tishreen University.
A lubricant (Lithium-Sodium) of Syrian petroleum-based stocks and
thickener material depends in its preparation on Skinless chicken fat, was
manufactured at different ratios.
A study of physical - chemical properties of manufactured grease types w
as
carried out (compared with Syrian standard specification 791/2008) by using
standard methods which included: grease state, penetration degree, drop point,
free acidity (as oleic acid)% by weight, grease resistence to water, evaporating
at 90° C, and corrosion of copper plate. Where the results show that the best
type of grease is of 30% ratio.
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